Conventional single ply roof coverings or membranes, in use since 1970, have experienced several problems involving ease of installation, poor light reflectivity resulting in higher energy costs, shrinkage resulting in seam failure, time consuming attachment, replacement and repair procedures, low tolerance of cold temperatures causing cracking and loss of flexibility and lower adhesive resistance to chemical attack. Conventional roofing employing single ply sheets of ethylene/propylene/butadiene (EPDM) copolymers have experienced leakage and seam failure due to membrane shrinkage. The introduction of seam tapes replacing adhesives have partially ameliorated this condition; however, the application of tapes is time consuming and encounters difficulties in repair and replacement. Single ply polyvinyl chloride (PVC)/plasticizer sheeting is presently more widely used for roofing since it offers several advantages over EPDM. For example, although more expensive, it is available in white or lightly tinted membranes for better light reflectivity, thereby realizing significant savings in energy costs. Also PVC possesses high resistance to a wide variety of potentially destructive chemicals. Notwithstanding these advantages, installation of PVC sheeting is associated with costly and time consuming heat-welded seams to insure watertight reliability. Moreover, in a few cases, problems with plasticizer migration has resulted in system failure. Sheeting of ethylene/propylene copolymer (TPO) and other thermoplastic olefin polymers have several advantages over the above including markedly reduced shrinkage, high reflectivity, good weatherability and improved impact and puncture resistance, thereby addressing and minimizing the prior causes of single ply roofing failure.
Various methods of attachment of the above sheeting to roofs have been used or proposed. These include mechanical fastening with screws and anchor plates through the membrane and into a roof deck; the ballasting of the membrane with rocks or alternative aggregates to hold the membrane in place and coating of both the substrate and the membrane with a contact adhesive, containing aromatic components, which requires extended curing time for the coated surfaces to bond. Additionally, the later method presents health hazards arising from noxious toluene or xylene fumes vaporized during the curing process.
Accordingly, it is an object of the present invention to overcome the above time consuming procedures and other deficiencies while retaining beneficial properties of single ply roofing including superior tear, peel and puncture resistance, low temperature tolerance to avoid cracking and resistance to chemical attack.
Another object is to provide a single ply roof covering which eliminates mechanical fastening, ballasting, heat welding, cure time and supplementary adhesive requiring time curing.
Still another object is to achieve ease of replacement or patching of a surface adhered to a single ply roofing element.
Yet another object is to provide improved single ply sheeting packaged in a continuous roll which is immediately ready for use after peeling off a silicone release backer strip.
These and other objects and advantages will become apparent from the following description and disclosure.